It has been conventionally known that, in the semiconductor device, leakage current in the insulating film between the interconnections add to the power consumption. Such leakage current has not much influential on the semiconductor device as a whole of the generation whose interconnection pitch exceeds 1 μm.
However, with the interconnection pitch being, e.g., not more than 1 μm, the leakage current becomes more influential on the power consumption due to the smaller interconnection pitches and the increased interconnection scales. When the circuit is formed with the interconnections of not more than 1 μm-pitch, the leakage current between the interconnections becomes to be influential on the characteristics and the lifetime of the semiconductor devices.
Presently, as a method of forming the interconnections of the semiconductor devices, the so-called damascene method is used. In the damascene method, first, interconnection trench of an interconnection pattern is formed in an insulating film by etching. Next, on the insulating film with the interconnection trench formed in, an interconnection material, such as copper or others, is deposited. Then, the excessive interconnection material on the insulating film is polished off by CMP (Chemical Mechanical Polishing) method to bury the interconnection material in the interconnection trench. Thus, the interconnection buried in the insulating film is formed.
The following are examples of related: Japanese Laid-open Patent Publication No. 2007-294854; F. Chen et al., IEEE IRPS Proceedings 43th Annual, pp. 501-507, 2005; A. Ishii et al., IEEE IITC Proceedings, pp. 21-23, 2005; and T. Imada et al., 2007 AMC Proceedings, P.V.2.
However, in the damascene method, in polishing the interconnection material by CMP method, the surface of the insulating film with the interconnection material buried in is chemically and mechanically damaged. Such damage of the insulating film surface causes increases of the leakage current, degradation of the TDDB (Time Dependent Dielectric Breakdown) characteristics, etc., which is one factor for decreases of the manufacturing yields and reliability of the semiconductor devices.